African Fossils Reveal Evolutionary Split Between Old World Monkeys and Apes

Ancient African fossils may have solved an evolutionary mystery. Researchers have discovered remains that reveal new information about the evolution of primates, and could show the oldest evidence of a split between Old World Monkeys and apes.

The new fossils were discovered in the Rukwa Rift Basin of Tanzania, and are about 25 million years old--that's significantly older than previous finds. The fossils actually document two majors groups of primates--one that contains the apes and humans of today and one that contains Old World Monkeys such as baboons and macaques.

Both of the primates that the fossils represent are actually two newly discovered, ancient species. The first one, named Rukwapithecus fleaglei, is an early hominoid represented by a mandible preserving several teeth. The other species, known as Nsungwepithecus gunnelli, is actually an early cercepithecoid that's represented by a tooth and a jaw fragment. Both of the species existed during the Oligocene epoch, and the new fossils have provided a wealth of evidence for researchers.

"The late Oligocene is among the least sampled intervals in primate evolutionary history, and the Rukwa field area provides a first glimpse of the animals that were alive at that time from Africa south of the equator," said Nancy Stevens, an associate professor of paleontology in Ohio University's Heritage College of Osteopathic Medicine, in a news release.

In fact, the evolutionary history of primates has remained largely elusive before these finds. Researchers have long argued about when these species diverged from one another, forming distinct populations from a common ancestor. These latest findings, though, have helped reconcile this disagreement.

"Fossils from the Rukwa Rift Basin in southwestern Tanzania provide the first real test of the hypothesis that these groups diverged so early, by revealing a novel glimpse into this late Oligocene terrestrial ecosystem," said Stevens.

The findings reveal that, in fact, apes and Old World monkeys diverged far earlier than once thought. It has given scientists and in-depth look at the process of evolution, and may allow them to further understand our own evolutionary history.

The findings are published in the journal Nature.